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Oxide System

In ceramic glaze calculation, a 'system' refers to a collection of glaze recipes that share a common set of oxides and material types (e.g. cone 10 dolomite mattes, cone 06 fritted boron glossies, cone 6 alumina matte, cone 8-10 crystalline) and preparation, application and firing methods. Also, a 'system' implies or states limits for each oxide beyond which unpredictable results are likely to occur. Ways of relating the oxide formulas of glazes to their physical fired results also imply confinement to a system.

For example, expansion calculations are relative within systems. For example, if you have a dolomite, whiting, feldspar, kaolin, silica glaze and you try a bunch of variations, the calculated expansions will give you an indication of which variations have higher and lower expansions. But if you introduce lithium carbonate, or boron frit, or zinc, for example, now you have a different system. Also, some oxides, like Li2O do not impose their expansions in a linear fashion, thus they compromise a system because they do not calculate as well. Another critical factor is melting: If a glaze is not completely melted the expansion calculation is invalid, the glaze is not within the system. A third factor: Crystalization: When a glass crystallizes its physical properties are different. A fourth factor: Non melting particles, like zircon, impose their expansions in a manner different than if they melt and participate in the glass chemistry.

Out Bound Links

  • (Glossary) Co-efficient of Thermal Expansion

    A measure of the reversible volume or length change of a ceramic material with temperature. The more the expansion during heating the more contraction must occur while cooling it back down. Expansion values are very small and recorded in scientific notation (e.g. 6.5 x 10-7 which is 0.00000065). Typ...

In Bound Links

  • (Glossary) Calculated Thermal Expansion

    Insight-live and desktop Insight calculate the thermal expansion of a glaze from its oxide chemistry. The number it reports is based on the contributing expansion factors and amounts of each oxide in the formula. These numbers are very small and recorded in scientific notation (e.g. 6.5 x 10-7 which...

  • (Glossary) Melting Temperature

    Unlike crystalline minerals, glazes do not have a specific melting temperature, they soften over a range of temperatures. And after they have been melted they become increasingly fluid and homogeneous. The softening process is not a linear one, this is especially so because raw glaze powders are a m...

  • (Videos) Lesson 1A - Comparing a Theoretical and a Real-World Feldspar

    This video is packed with information. Transcript: Video 1C - Comparing a Theoretical and a Real-World Feldspar 1 Entering recipes, materials and the materials database, theoretical materials,...

By Tony Hansen

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